Objective lens system for microscopes

ABSTRACT

An objective lens system for microscopes having a large N.A. and a long working distance comprising a first positive lens component, a second single or cemented meniscus lens component, a third negative cemented meniscus lens component and a fourth positive lens component. Said objective lens system is so designed as to satisfy the conditions enumerated hereunder: 
     (1) f/4&lt;d 6  +d 7  &lt;f/1.5 
     (2) 0.1f&lt;r 5  &lt;0.35f 
     0.1f&lt;-r 6  &lt;0.35f 
     (3) ν 2  &gt;40 
     ν 5&#39;  ν 6  &gt;55 
     ν 4  &lt;40

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a low magnification objective lenssystem for microscopes, and more specifically an objective lens systemconsisting of four lens components and having a long working distanceand a large numerical aperture.

(B) Description of the Prior Art

As plan objective lens systems for microscopes, there haveconventionally been known those which comprise two doublet lenscomponents or four lens elements, etc. Most of the conventional lowmagnification objective lens systems of this type for microscopes hadsmall N.A. of about 0.1 and working distances of about 0.2 whenconverted into distances corresponding to f=1. Further, these objectivelens systems for microscopes were not satisfactory from a viewpoint ofcorrection of aberrations since coma could not be corrected favorablyand relatively large astigmatic differences remained in these objectivelens systems for microscopes.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide an objectivelens system for microscopes which has a relatively large N.A. value anda long working distance and wherein aberrations are favorably corrected.

The objective lens system according to the present invention has such acomposition as shown in FIG. 1, FIG. 4 or FIG. 6. Speaking moreconcretely, the objective lens system according to the present inventioncomprises four lens components: a first positive lens component, asecond single or cemented meniscus lens component, a third negativecemented lens component and a fourth positive lens component. Theobjective lens system according to the present invention ischaracterized by the fact that it satisfies the conditions definedbelow:

(1) f/4<d₆ +d₇ <f/1.5

(2) 0.1F<r₅ <0.35f

0.1f<-r₆ <0.35f

(3) ν₂ >40

ν₅,ν₆ >55

ν₄ <40

Wherein the reference symbols represent as follows:

D₆ +d₇ : thickness of the third lens component

R₅ and r₆ : radii of curvature on the image side surface of the secondlens component and on the object side surface of the third lenscomponent

ν₂,ν₄,ν₅ and ν₆ : Abbe's numbers of the second lens component (or theobject side lens element when the second lens component is a cementeddoublet), both the elements of the third lens component and the fourthlens component.

In case of designing such an objective lens system for microscopeshaving a long working distance and a large numerical aperture as isprovided by the present invention, the most difficult problem lies infavorably correcting chromatic aberration. That is to say, it is mostimportant to realize the most favorable chromatic aberration within apractically permissible range by properly selecting, disposition of lenselements made of usable kinds of glass materials and distribution ofrefractive powers.

In order to favorably correct chromatic aberration mentioned above, itis required to limit dispersion of rays within a narrow range on theobject side. For this purpose, a thick lens component must be arrangedwithin an area near the object to be observed where the rays have largeangles relative to the optical axis. However, arranging a thick lenscomponent near the object will be contradictory to the object of thepresent invention to prolong the working distance. Therefore, theobjective lens system according to the present invention uses a thicklens component (the third lens component) in the rear lens group whichis designed as a cemented component for correcting chromatic aberration.Thickness (d₆ +d₇) of the third lens component is so selected as to bewithin the range defined by the condition (1). If d₆ +d₇ is smaller thanf/4 in the condition (1), coma will be extremely aggravated, therebydegrading symmetry of coma. If d₆ +d₇ exceeds f/1.5, in contrast, itwill be difficult to correct chromatic aberration favorably.

As an objective lens system having a flat image surface, there haveconventionally been known a lens system wherein a lens component havinga strongly concave surface on the image side is arranged in the rearlens group. However, this type of objective lens system has a defect toaggravate chromatic spherical aberration. Further, there haveconventionally been known an objective lens system which is so designedas to provide a flat image surface by arranging a strongly meniscus lensas the front lens component and imparting a strongly negative refractivepower to the object side concave surface of said front lens component.However, such a lens system is undesirable since it has a shorteffective working distance. Further, increasing thickness of the frontlens component is also undesirable for the same reason.

The objective lens system according to the present invention is designedas a Gauss type lens system for the purpose of preferably avoidingcorrecting curvature of field by a front lens component and performingsuch correction by the other lens components. Speaking more concretelywith reference to the objective lens system according to the presentinvention, radii of curvature r₅ and r₆ on the mutually facing surfacesof the second and third lens components are defined within the ranged ofthe condition (2) so as to correct curvature of field favorably. If theupper limits are exceeded in condition (2), Pettzval's sum is increased,thereby degrading flatness of the image surface. If the radii ofcurvature r₅ and -r₆ are smaller than the lower limits, coma will beaggravated, thereby making it impossible to obtain a proper balancebetween Petzval's sum and coma.

Finally, chromatic aberration is favorably corrected in the objectivelens system according to the present invention by selecting large Abbe'snumbers for the respective lens components as defined in the condition(3) and using a combination of highly and lowly dispersive materials forthe third lens component. It will be impossible to correct chromaticaberration favorably when the condition (3) is not satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view illustrating the compositions of theEmbodiments 1 and 2 of the present invention;

FIG. 2 shows curves illustrating the aberration characteristics of theEmbodiment 1;

FIG. 3 shows graphs illustrating the aberration characteristics of theEmbodiment 2;

FIG. 4 illustrates a sectional view showing the compositions ofEmbodiments 3, 5 and 6;

FIG. 5 illustrates curves showing the aberration characteristics of theEmbodiment 3;

FIG. 6 illustrates a sectional view showing the composition of theEmbodiment 4;

FIG. 7 shows graphs visualizing the aberration characteristics of theEmbodiment 4;

FIG. 8 shows curves visualizing the aberration characteristics of theEmbodiment 5; and

FIG. 9 shows curves illustrating the aberration characteristics of theEmbodiment 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Now, some preferred embodiments of the present invention will bedescribed detailedly below:

    ______________________________________                                        Embodiment 1                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.3638                                    ______________________________________                                        r.sub.1 = 1.0662                                                                          d.sub.1 = 0.0774                                                                         n.sub.1 = 1.77250                                                                        ν.sub.1 = 49.60                          r.sub.2 -0.5293                                                                           d.sub.2 = 0.0285                                                  r.sub.3 = 0.2136                                                                          d.sub.3 = 0.0892                                                                         n.sub.2 = 1.75500                                                                        ν.sub.2 = 52.33                          r.sub.4 = 0.8616                                                                          d.sub.4 = 0.0334                                                                         n.sub.3 = 1.73520                                                                        ν.sub.3 = 41.08                          r.sub.5 = 0.1374                                                                          d.sub.5 = 0.1628                                                  r.sub.6 = -0.1352                                                                         d.sub.6 = 0.2434                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.8439                                                                          d.sub.7 = 0.0941                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.2823                                                                         d.sub.8 = 0.0214                                                  r.sub.9  = 8.8577                                                                         d.sub.9 = 0.1143                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.6290                                                            ______________________________________                                    

    ______________________________________                                        Embodiment 2                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.3603                                    ______________________________________                                        r.sub.1 = 0.9961                                                                          d.sub.1 = 0.0713                                                                         n.sub.1 = 1.79500                                                                        ν.sub.1 = 45.27                          r.sub.2 = -0.6766                                                                         d.sub.2 = 0.0238                                                  r.sub.3 = 0.2095                                                                          d.sub.3 = 0.0911                                                                         n.sub.2 = 1.75500                                                                        ν.sub.2 = 52.33                          r.sub.4 = 0.7694                                                                          d.sub.4 = 0.0371                                                                         n.sub.3 = 1.73520                                                                        ν.sub.3 = 41.08                          r.sub.5 = 0.1352                                                                          d.sub.5 = 0.1771                                                  r.sub.6 = -0.1362                                                                         d.sub.6 = 0.2283                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.8967                                                                          d.sub.7 = 0.0797                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.2796                                                                         d.sub.8 =  0.0146                                                 r.sub.9 = 6.5466                                                                          d.sub.9 = 0.1098                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.5686                                                            ______________________________________                                    

    ______________________________________                                        Embodiment 3                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4190                                    ______________________________________                                        r.sub.1 = 3.3947                                                                          d.sub.1 = 0.0894                                                                         n.sub.1 = 1.80610                                                                        ν.sub.1 = 40.95                          r.sub.2 = -0.6104                                                                         d.sub.2 = 0.0249                                                  r.sub.3 = 0.2267                                                                          d.sub.3 = 0.0991                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 49.60                          r.sub.4 = -0.3508                                                                         d.sub.4 = 0.0275                                                                         n.sub.3 = 1.72000                                                                        ν.sub.3 = 42.08                          r.sub.5 = 0.1658                                                                          d.sub.5 = 0.1362                                                  r.sub.6 = -0.1420                                                                         d.sub.6 = 0.2922                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.7763                                                                          d.sub.7 = 0.1122                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.3476                                                                         d.sub.8 =  0.0213                                                 r.sub.9 = 3.2004                                                                          d.sub.9 = 0.1253                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.7606                                                            ______________________________________                                    

    ______________________________________                                        Embodiment 4                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.3781                                    ______________________________________                                        r.sub.1 = 1.5323                                                                          d.sub.1 = 0.0758                                                                         n.sub.1 = 1.75500                                                                        ν.sub.1 = 52.33                          r.sub.2 = -0.5965                                                                         d.sub.2 = 0.0075                                                  r.sub.3 = 0.1647                                                                          d.sub.3 = 0.0659                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 49.60                          r.sub.5 = 0.1435                                                                          d.sub.5 = 0.2139                                                  r.sub.6 = -0.1196                                                                         d.sub.6 = 0.2262                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.7513                                                                          d.sub.7 = 0.1088                                                                         n.sub.5 = 1.49250                                                                        ν.sub.5 = 81.90                          r.sub.8 = -0.2819                                                                         d.sub.8 = 0.0262                                                  r.sub.9 = 10.9245                                                                         d.sub.9 = 0.1125                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 =  60.27                         r.sub.10 = 0.6141                                                             ______________________________________                                    

    ______________________________________                                        Embodiment 5                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4327                                    ______________________________________                                        r.sub.1 = 0.4378                                                                          d.sub.1 = 0.0788                                                                         n.sub.1 = 1.75500                                                                        ν.sub.1 = 52.33                          r.sub.2 = -1.5332                                                                         d.sub.2 = 0.0072                                                  r.sub.3 = 0.2984                                                                          d.sub.3 = 0.0719                                                                         n.sub.2 = 1.76200                                                                        ν.sub.2 = 40.20                          r.sub.4 = -0.6620                                                                         d.sub.4 = 0.0249                                                                         n.sub.3 = 1.61340                                                                        ν.sub.3 = 43.84                          r.sub.5 = 0.1665                                                                          d.sub.5 = 0.1372                                                  r.sub.6 = -0.1427                                                                         d.sub.6 = 0.3226                                                                         n.sub.4 = 1.66680                                                                        ν.sub.4 = 33.04                          r.sub.7 = 1.3593                                                                          d.sub.7 = 0.1094                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.60                          r.sub.8 = -0.3215                                                                         d.sub.8 =  0.0214                                                 r.sub.9 = 2.1861                                                                          d.sub.9 = 0.0864                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.9477                                                            ______________________________________                                    

    ______________________________________                                        Embodiment 6                                                                            f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4286                                    ______________________________________                                        r.sub.1 = 0.4452                                                                          d.sub.1 = 0.0779                                                                         n.sub.1 = 1.80610                                                                        ν.sub.1 = 40.95                          r.sub.2 = -2.3115                                                                         d.sub.2 = 0.0071                                                  r.sub.3 = 0.2937                                                                          d.sub.3 = 0.0698                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 49.60                          r.sub.4 = -0.9199                                                                         d.sub.4 = 0.0246                                                                         n.sub.3 = 1.61340                                                                        ν.sub.3 = 43.84                          r.sub.5 = 0.1663                                                                          d.sub.5 = 0.1513                                                  r.sub.6 = -0.1478                                                                         d.sub.6 = 0.3137                                                                         n.sub.4 = 1.64769                                                                        ν.sub.4 = 33.80                          r.sub.7 = 1.2115                                                                          d.sub.7 = 0.1124                                                                         n.sub.5 = 1.49250                                                                        ν.sub.5 = 81.90                          r.sub.8 = -0.3252                                                                         d.sub.8 =  0.0226                                                 r.sub.9 = 2.1795                                                                          d.sub.9 = 0.0849                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.9458                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element. Of the embodiments described above, Embodiments1 and 2 have such compositions as are shown in FIG. 1, whereasEmbodiment 3 has such a composition as is shown in FIG. 4. That is tosay, all of these embodiments comprise a comented meniscus lens as thesecond lens component. The Embodiment 4 is an objective lens systemhaving such a composition as shown in FIG. 6 in which the second lenscomponent is a single meniscus lens element and the reference symbolsr₄, d₄, n₃ or ν₃ are skipped. Further, the Embodiments 5 and 6 areobjective lens systems so composed as shown in FIG. 4.

As is clearly understood from the foregoing descriptions andembodiments, the objective lens system according to the presentinvention has a larger N.A. value and a longer working distance thanthose of the conventional objective lens systems of the similar types.Further, in contrast to the conventional objective lens systems of thistype which produced relatively remarkable spherical aberration for gline, the objective lens system according to the present invention canreduce spherical aberration to about half the level, and correct comaand astigmatic difference more favorably.

I claim:
 1. An objective lens system for microscopes comprising a firstpositive lens component, a second meniscus lens component, a thirdnegative cemented doublet meniscus lens component and a fourth positivelens component, and said lens system satisfying the conditionsenumerated hereunder:(1) f/4<d₆ +d₇ <f/1.5 (2) 0.1f<r₅ <0.35f0.1f<-r₆<0.35f (3) ν₂ >40ν₅,ν₆ >55 ν₄ <40wherein the reference symbol d₆ +d₇represents thickness of the third lens component, the reference symbolsr₅ and r₆ designate radii of curvature on the image side surface of thesecond lens component and on the object side surface of the third lenscomponent respectively, the reference symbols ν₂, ν₄, ν₅, ν₆ denoteAbbe's numbers of the second lens component, both the elements of thethird lens component and the fourth lens component respectively and thereference symbol f represents total focal length of the lens system as awhole.
 2. An objective lens system for microscopes according to claim 1wherein said second lens component is a cemented doublet meniscus lens.3. An objective lens system for microscopes according to claim 2 havingthe following numerical data:

    ______________________________________                                                  f = 1.0  N.A. = 0.13                                                                             W.D. = 0.3638                                    ______________________________________                                        r.sub.1 = 1.0662                                                                          d.sub.1 = 0.0774                                                                         n.sub.1 = 1.66250                                                                        ν.sub.1 = 49.60                          r.sub.2 = -0.5293 -                                                                       d.sub.2 = 0.0285                                                  r.sub.3 = 0.2136                                                                          d.sub.3 = 0.0892                                                                         n.sub.2 = 1.75500                                                                        ν.sub.2 = 52.33                          r.sub.4 = 0.8616                                                                          d.sub.4 = 0.0334                                                                         n.sub.3 = 1.73520                                                                        ν.sub.3 = 41.08                          r.sub.5 = 0.1374                                                                          d.sub.5 = 0.1628                                                  r.sub.6 = -0.1352                                                                         d.sub.6 = 0.2434                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.8439                                                                          d.sub.7 = 0.0941                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.2823                                                                         d.sub.8 = 0.0214                                                  r.sub.9 =  8.8577                                                                         d.sub.9 = 0.1143                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.6290                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.
 4. An objective lens system for microscopesaccording to claim 2 having the following numerical data:

    ______________________________________                                                  f = 1.0 N.A. = 0.13                                                                              W.D. = 0.3603                                    ______________________________________                                        r.sub.1 = 0.9961                                                                          d.sub.1 = 0.0713                                                                         n.sub.1 = 1.79500                                                                        ν.sub.1 = 45.27                          r.sub.2 = -0.6766                                                                         d.sub.2 = 0.0238                                                  r.sub.3 = 0.2095                                                                          d.sub.3 = 0.0911                                                                         n.sub.2 = 1.75500                                                                        ν.sub.2 = 52.33                          r.sub.4 = 0.7694                                                                          d.sub.4 = 0.0371                                                                         n.sub.3 = 1.73520                                                                        ν.sub.3 = 41.08                          r.sub.5 = 0.1352                                                                          d.sub.5 = 0.1771                                                  r.sub.6 = 0.1362                                                                          d.sub.6 = 0.2283                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.8967                                                                          d.sub.7 = 0.0797                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.2796                                                                         d.sub.8 = 0.0146                                                  r.sub.9 =  6.5466                                                                         d.sub.9 = 0.1098                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.5686                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.
 5. An objective lens system for microscopesaccording to claim 2 having the following numerical data:

    ______________________________________                                                  f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4190                                    ______________________________________                                        r.sub.1 = 3.3947                                                                          d.sub.1 = 0.0894                                                                         n.sub.1 = 1.80610                                                                        ν.sub.1 = 40.95                          r.sub.2 = -0.6104                                                                         d.sub.2 = 0.0249                                                  r.sub.3 = 0.2267                                                                          d.sub.3 = 0.0991                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 49.60                          r.sub.4 = -0.3508                                                                         d.sub.4 = 0.0275                                                                         n.sub.3 = 1.72000                                                                        ν.sub.3 = 42.08                          r.sub.5 = 0.1658                                                                          d.sub.5 = 0.1362                                                  r.sub.6 = -0.1420                                                                         d.sub.6 = 0.2922                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.7763                                                                          d.sub.7 = 0.1122                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.34                          r.sub.8 = -0.3476                                                                         d.sub.8 = 0.0213                                                  r.sub.9 = 3.2004                                                                          d.sub.9 = 0.1253                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.7606                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.
 6. An objective lens system for microscopesaccording to claim 1 having the following numerical data:

    ______________________________________                                                  f = 1.0 N.A. = 0.13                                                                              W.D. = 0.3781                                    ______________________________________                                        r.sub.1 = 1.5323                                                                          d.sub.1 = 0.0758                                                                         n.sub.1 = 1.75500                                                                        ν.sub.1 = 52.33                          r.sub.2 = -0.5965                                                                         d.sub.2 = 0.0075                                                  r.sub.3 = 0.1647                                                                          d.sub.3 = 0.0659                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 49.60                          r.sub.5 = 0.1435                                                                          d.sub.5 = 0.2139                                                  r.sub.6 = -0.1196                                                                         d.sub.6 = 0.2262                                                                         n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                          r.sub.7 = 0.7513                                                                          d.sub.7 = 0.1088                                                                         n.sub.5 = 1.49250                                                                        ν.sub.5 = 81.90                          r.sub.8 = -0.2819                                                                         d.sub.8 = 0.0262                                                  r.sub.9 = 10.9245                                                                         d.sub.9 = 0.1125                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10  = -0.6141                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.
 7. An objective lens system for microscopesaccording to claim 2 having the following numerical data:

    ______________________________________                                                  f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4327                                    ______________________________________                                        r.sub.1 = 0.4378                                                                          d.sub.1 = 0.0788                                                                         n.sub.1 = 1.75500                                                                        ν.sub.1 = 52.33                          r.sub.2 = -1.5332                                                                         d.sub.2 = 0.0072                                                  r.sub.3 = 0.2984                                                                          d.sub.3 = 0.0719                                                                         n.sub.2 = 1.76200                                                                        ν.sub.2 = 40.20                          r.sub.4 = -0.6620                                                                         d.sub.4 = 0.0249                                                                         n.sub.3 = 1.61340                                                                        ν.sub.3 = 43.84                          r.sub.5 = 0.1665                                                                          d.sub.5 = 0.1372                                                  r.sub.6 = -0.1427                                                                         d.sub.6 = 0.3226                                                                         n.sub.4 = 1.66680                                                                        ν.sub.4 = 33.04                          r.sub.7 = 1.3593                                                                          d.sub.7 = 0.1094                                                                         n.sub.5 = 1.49700                                                                        ν.sub.5 = 81.60                          r.sub.8 = -0.3215                                                                         d.sub.8 = 0.0214                                                  r.sub.9 = 2.1861                                                                          d.sub.9 = 0.0864                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.9447                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.
 8. An objective lens system for microscopesaccording to claim 2 having the following numerical data:

    ______________________________________                                                  f = 1.0 N.A. = 0.13                                                                              W.D. = 0.4286                                    ______________________________________                                        r.sub.1 = 0.4452                                                                          d.sub.1 = 0.0779                                                                         n.sub.1 = 1.80610                                                                        ν.sub.1 = 40.95                          r.sub.2 = -2.3115                                                                         d.sub.2 = 0.0071                                                  r.sub.3 = 0.2937                                                                          d.sub.3 = 0.0698                                                                         n.sub.2 = 1.77250                                                                        ν.sub.2 = 40.60                          r.sub.4 = -0.9199                                                                         d.sub.4 = 0.0246                                                                         n.sub.3 = 1.61340                                                                        ν.sub.3 = 43.84                          r.sub.5 = 0.1663                                                                          d.sub.5 = 0.1513                                                  r.sub.6 = -0.1478                                                                         d.sub.6 = 0.3137                                                                         n.sub.4 = 1.64769                                                                        ν.sub.4 = 33.80                          r.sub.7 = 1.2115                                                                          d.sub.7 = 0.1124                                                                         n.sub.5 = 1.49250                                                                        ν.sub.5 = 81.90                          r.sub.8 = -0.3252                                                                         d.sub.8 = 0.0226                                                  r.sub.9 = 2.1795                                                                          d.sub.9 = 0.0849                                                                         n.sub.6 = 1.62041                                                                        ν.sub.6 = 60.27                          r.sub.10 = -0.9458                                                            ______________________________________                                    

wherein the reference symbols r₁ through r₁₀ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₉ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ through n₆denote refractive indices of the respective lens elements and thereference symbols ν₁ through ν₆ represent Abbe's numbers of therespective lens element.